King's Colour

King's Color is a chess variant, played on a tri-colored hex-hex board. Each king is confined to a 3x3 castle surrounded by a wall. The other pieces are rooks or bishops, which promote to queens. The big twist to this game is that when the king moves onto a different color, all the rooks become bishops, and all the bishops on the new color become rooks. Capturing is limited to pieces inside the castle, which influences the game to be oriented around checkmate rather than attrition.